This application claims the priority of 196 25 502.3, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a device for controlling the longitudinal movement of a motor vehicle, with a user-actuatable regulating element which controls the vehicle longitudinal movement with both an accelerating and a decelerating effect.
In known devices of this type, the user-actuatable regulating element is preferably a control stick operated with one hand. The control stick serves, instead of a conventional accelerator and brake pedal assembly, as a user interface for controlling the vehicle longitudinal speed, specifically both for increasing and decreasing the latter. If required, the regulating element may additionally serve for controlling the vehicle transverse movement of the vehicle, i.e. steering of the vehicle. Arrangements of this type are described in U.S. Pat. No. 3,022,850 and in H. Bubb, Arbeitsplatzfahrer--eine ergonomische Studie [Workstation Driver--an ergonomic study], Automobil-Industrie [Automobile Industry] March 1985, page 265.
Preferably, during forward driving, an actuation of the regulating element in a first actuation direction, for example forwards, brings about a speed increase and an actuation in an opposite second actuation direction, i.e., for example, backwards, brings about a speed reduction, so that the actuation of the regulating element corresponds intuitively to the vehicle behavior required by the driver. The speed to be set or the positive acceleration or negative acceleration (deceleration) to be set is fixed according to a predetermined characteristic as a function of the deflection of the regulating element or of the actuating force exerted on the regulating element.
The easily perceived assignment of the actuation direction of the regulating element to the desired vehicle behavior may be unsatisfactory for vehicles which can be driven not only forwards, but also backwards. For if the functionality of the forward driving mode is maintained for the regulating element for reversing purpose, the intuitive relationship between the actuation direction of the regulating element and the effect on the vehicle dynamics is lost on account of the opposite direction of vehicle movement. That is, an actuation of the regulating element in the direction of vehicle movement would then not bring about an increase, but a decrease in the reversing speed.
We are aware of a proposed remedy in the form of a regulating element arrangement for controlling the longitudinal speed and/or the angle of a motor vehicle, in which the assignment of the speed increase function and of the speed reduction function respectively to the first and second actuation directions of the regulating element is inverted during reversing in comparison with that during forward driving. This ensures that, both during forward driving and reversing, an actuation of the regulating element in the direction of vehicle movement brings about a speed increase and an actuation of the regulating element in the opposite direction brings about a speed reduction. An automatic changeover can be provided between these assignments when the reverse gear of a vehicle transmission is engaged and disengaged.
Regardless of whether such an assignment change is or is not provided in the conventional arrangements with a uniform regulating element for controlling the entire longitudinal vehicle dynamics, a further operating element, conventionally a gear-shift lever, must be actuated during the change between forward driving and reversing.
The present invention has as an object the provision of a device which controls the longitudinal vehicle dynamics with high operating comfort both during forward driving and during reversing.
The foregoing object has been solved in accordance with the present invention by a device having a forward driving mode and a maneuvering mode as driving modes. In the forward driving mode, the vehicle is movable solely forwards and, when the regulating element is actuated in a first actuation direction, the vehicle is acceleratable to an extent dependent on deflection or actuating force of the regulating element. When the regulating element is actuated in a second actuation direction, the vehicle is deceleratable to an extent dependent on the deflection or actuating force of the regulating element, and in the maneuvering mode, the vehicle is movable forwards when the regulating element is actuated in the one actuation direction and is movable backwards when the regulating element is actuated-in the other actuation direction.
In this improved device, at least two selectable driving modes, between which the vehicle driver can change over, are provided, specifically a forward driving mode and a maneuvering mode. In the forward driving mode, the longitudinal vehicle movement is controlled, via a user-actuatable uniform regulating element, with both an accelerating and decelerating effect. In the maneuvering mode, the vehicle can be moved selectively in the forward direction or the backward direction solely as a function of the actuation of the uniform regulating element, for example in that forward driving is activated by actuating the regulating element forwards and reversing is activated when the regulating element is actuated backwards.
Thus, during maneuvering with the device of the present invention, an associated gear selector lever does not have to be actuated whenever there is a change between forward driving and reversing. Consequently, a reversing stage is not required for a gear selector lever which may be present, because the corresponding actuation of the regulating element controlling the longitudinal vehicle movement already induces the selection of reverse gear in the transmission. The changeover between the forward driving mode and the maneuvering mode which is to be carried out by the driver, for example via a corresponding operating button, brings about the associated changeover between the control functions of the regulating element which are different in the two driving modes.
In the device of the present invention, the maximum speed which can be reached in the maneuvering mode is kept lower than the maximum possible speed which can be reached by the vehicle in the forward driving mode. Preferably, the maximum speed in the maneuvering mode is markedly lower than the maximum speed of the vehicle, in order to restrict the maneuvering mode to the maneuvering of the vehicle at low speeds, for example lower than 20 km/h.
Furthermore, a standing brake function which brings the vehicle to a standstill or keeps it standing can be active in a middle actuation range of the regulating element. Only when the regulating element is actuated beyond this range is the vehicle moved forwards or backwards, depending on the actuation direction of the regulating element. The provision of the actuation range of the regulating element together with a standing brake function allows transitions which are smooth in terms of driving dynamics between forward driving and reversing phases during maneuvering.
A third driving mode in the form of a reversing mode can also be provided in accordance with an embodiment of the present invention, which may likewise be selected by the driver via a corresponding operating element and in which the vehicle can be moved solely in reverse. The user-actuatable regulating element for controlling the longitudinal vehicle movement serves, in this embodiment, both for increasing and for decreasing the reversing speed. The assignment between the actuation direction of the regulating element for increasing and decreasing the vehicle speed can be identical to that of the forward driving mode or else be inverted relative thereto.
According to another aspect of the present invention, the respective actuation of the regulating element can be advantageously assigned to the vehicle operating parameter or variable activated thereby and determining the driving dynamics, with the aid of predetermined characteristics which are selected so as to be steeper for the forward driving mode than for the maneuvering mode. Thereby, with the regulating element being actuated in the same way, the longitudinal vehicle movement can be set more sensitively in the maneuvering mode than in the forward driving mode.
In a further embodiment, a change can be instantaneous or gradual according to predetermined transition characteristics from the previous value to the new value of the control variable influenced by the actuation of the regulating element, during the changeover between the forward driving mode and the maneuvering mode. The change in the driving speed during such changeover operations can consequently be predetermined in the way desired in each situation.